Police said they admitted buying plastic bottles, aluminum foil and household chemicals before assembling the devices.

“They were throwing them at both property and people,” Unified Fire Authority Capt. Clint Mecham told KUTV-TV, adding that nobody was injured. “This goes well beyond a teenage prank.”

Gill, who was 18 at the time of her June 8 pageant win, was booked on suspicion of detonating an incendiary device. She didn’t appear on the Salt Lake County jail roster Monday morning, and no phone number for her was listed.

It wasn’t immediately clear if any of the four had an attorney.

Gill defeated eight other beauty contestants earlier this summer, showing off her years of piano training with a Scott Joplin number and taking home a $2,000 (U.S.) scholarship.